Gas-phase thermochemistry of the early cationic transition-metal sulfides of the second row: YS +, ZrS +, and NbS +

Abstract

The gas-phase reactivity of YS +, ZrS +, and NbS + towards oxygen-transferring reagents such as H 2O, CO, CO 2, and COS is investigated using guided-ion beam (GIB) and Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry. A lower limit of D 0(M +–S) > 4.50 ± 0.04 eV for the sulfur binding energy is derived from the exothermic formation of MS + in the reaction of all three atomic metal ions, M +, with CS 2. Upper limits for D 0(M +–S) are determined by collision-induced dissociation of MS + with Xe. The O-transfer experiments carried out in the GIB instrument lead to several estimates for D 0(M +–S), which are further refined by equilibrium constants K eq derived from the reaction MS + + H 2O → MO + + H 2S and its reverse. Overall assessment of the results from ion–molecule reactions, collision-induced dissociation, and equilibrium measurements yields the 0 K bond energies of D 0(Y +–S) = 5.49 ± 0.18 eV, D 0(Zr +–S) = 5.69 ± 0.10 eV, D 0(Nb +–S) = 5.20 ± 0.21 eV, D 0(Y +–CS) = 1.42 ± 0.08 eV, D 0(Zr +–CS) = 2.67 ± 0.11 eV, and D 0(Nb +–CS) = 2.51 ± 0.11 eV, and heats of formation for Δ f H 0(YOS +) = 6.59 ± 0.37 eV, Δ f H 0(ZrOS +) = 8.45 ± 0.33 eV, Δ f H 0(NbOS +) = 9.05 ± 0.27 eV, Δ f H 0(YS 2 +) = 6.96 ± 0.70 eV, and Δ f H 0(ZrS 2 +) = 9.34 ± 0.73 eV.